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  • 1.
    Duan, Ran
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Acid-Catalyzed Synthesis of Foamed Materials from Renewable Sources2014In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 53, no 45, p. 17597-17603Article in journal (Refereed)
    Abstract [en]

    In this study, lightweight biobased foamed materials were successfully synthesized by the modification of renewable polysaccharides, such as starch and microcrystalline cellulose. Low-cost and nontoxic organic acids were utilized as catalysts in the first-step esterification reaction of the synthesis. The effects of different reaction conditions on the water absorbency and weight loss of freeze-casted polysaccharide–citrate–chitosan foams are discussed. Physical properties, such as pore-size distributions and compressive stress–strain curves, of the foams were determined. The characterization results show that the amide bonds formed between the carboxylic acid groups of polysaccharide–citrate and the amino groups of chitosan are crucial to the foamed material’s performance.

  • 2.
    Gorski, Dmitri
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Hill, Jan
    QualTech AB (Previously Norske Skog ASA), SE-282 21, Tyringe, Sweden.
    Improved quality of SC magazine paper through enhanced fibre development using the ATMP process2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 1, p. 35-41Article in journal (Refereed)
    Abstract [en]

    A pilot scale refining trial was conducted using the ATMP (Advanced Thermomechanical Pulp) refining concept with White spruce as raw material. Low-intensity TMP and high-intensity TMP with mechanical pre-treatment of chips were compared to ATMP (Mg+P), where development of fibres was enhanced using hydrogen peroxide and magnesium hydroxide. The main goal of the trial was to evaluate the potential of using ATMP process for production of SC (supercalendered) magazine paper. SC paper is especially demanding when it comes to the paper surface structure which is strongly influenced by the development of fibre properties.

    Improvement in individual fibre properties such as flexibility, fibre split index and fibre surface area index achieved using ATMP process was found to translate into decreased surface roughness and air permeability of calendered laboratory sheets. Both the refining process configuration and the addition of process chemicals were found to have significant impacts though the process configuration had major role. The influence of process chemicals on PPS was mainly pronounced after second stage refining. The magnitude of surface roughening (fibre rising) was found to be influenced mainly by the process configuration.

  • 3.
    Halvarsson, Sören
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Manufacture of straw MDF and fibreboards2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The purpose of this thesis was to develop an economical, sustainable, and environmentally friendly straw Medium Density Fibreboard (MDF) process, capable of full-scale manufacturing and to produce MDF of requested quality. The investigated straw was based on wheat (Triticum aestivum L.) and rice (Oryzae sativa L.). In this thesis three different methods were taken for manufacture of straw MDF; (A) wheat-straw fibre was blowline blended with melamine-modified urea-formaldehyde (MUF), (B) rice-straw fibre was mixed with methylene diphenyl diisocyanate (MDI) in a resin drum-blender, and (C) wheat-straw fibre was activated in the blowline by the addition of Fenton’s reagent (H2O2/Fe2+) for production of non-resin MDF panels.  The MUF/wheat straw MDF panels were approved according to the requirements of the EN standard for MDF (EN 622-5, 2006). The MDI/rice-straw MDF panels were approved according to requirements of the standard for MDF of the American National Standard Institute (ANSI A208.2-2002). The non-resin wheat-straw panels showed mediocre MDF panel properties and were not approved according to the requirements in the MDF standard. The dry process for wood-based MDF was modified for production of straw MDF. The straw MDF process was divided into seven main process steps.

    1. 1.       Size-reduction (hammer-milling) and screening of straw
    2. 2.       Wetting and heating of straw
    3. 3.       Defibration
    4. 4.       Resination of straw fibre
    5. 5.       Mat forming
    6. 6.       Pre-pressing
    7. 7.       Hot-pressing

     

     

     

    The primary results were that the straw MDF process was capable of providing satisfactory straw MDF panels based on different types of straw species and adhesives. Moreover, the straw MDF process was performed in pilot-plant scale and demonstrated as a suitable method for producing straw MDF from straw bales to finished straw MDF panels. In the environmental perspective the agricultural straw-waste is a suitable source for producing MDF to avoid open field burning and to capture carbon dioxide (CO2), the biological sink for extended time into MDF panels, instead of converting straw directly into bio energy or applying straw fibre a few times as recycled paper. Additionally, the straw MDF panels can be recycled or converted to energy after utilization.

    A relationship between water retention value (WRV) of resinated straw fibres, the thickness swelling of corresponding straw MDF panels, and the amount of applied adhesive was determined. WRV of the straw fibre increased and the TS of straw MDF declined as a function of the resin content. The empirical models developed were of acceptable significance and the R2 values were 0.69 (WRV) and 0.75 (TS), respectively. Reduced thickness swelling of MDF as the resin content is increased is well-known. The increase of WRV as a function of added polymers is not completely established within the science of fibre swelling. Fortunately, more fundamental research can be initiated and likely a simple method for prediction of thickness swelling of MDF by analysis of the dried and resinated MDF fibres is possible.

  • 4.
    He, Jie
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    GASIFICATION-BASED BIOREFINERY FOR MECHANICAL PULP MILLS2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The modern concept of "biorefinery" is dominantly based on chemical pulp mills to create more value than cellulose pulp fibres, and energy from the dissolved lignins and hemicelluloses. This concept is characterized by the conversion of biomass into various biobased products. It includes thermochemical processes such as gasification and fast pyrolysis. In mechanical pulp mills, the feedstock available to the gasification-based biorefinery is significant, including logging residues, bark, fibre material rejects, biosludges and other available fuels such as peat, recycled wood, and paper products. This work is to study co-production of bio-automotive fuels, biopower, and steam via gasification in the context of the mechanical pulp industry.

     

    Biomass gasification with steam in a dual-fluidized bed gasifier (DFBG) was simulated with ASPEN Plus. From the model, the yield and composition of the syngas and the contents of tar and char can be calculated. The model has been evaluated against the experimental results measured on a 150 KWth Mid Sweden University (MIUN) DFBG. The model predicts that the content of char transferred from the gasifier to the combustor decreases from 22.5 wt.% of the dry and ash-free biomass at gasification temperature 750 ℃ to 11.5 wt.% at 950 ℃, but is insensitive to the mass ratio of steam to biomass (S/B). The H2 concentration is higher than that of CO under normal DFBG operating conditions, but they will change positions when the gasification temperature is too high above about 950 ℃, or the S/B ratio is too far below about 0.15. The biomass moisture content is a key parameter for a DFBG to be operated and maintained at a high gasification temperature. The model suggests that it is difficult to keep the gasification temperature above 850 ℃ when the biomass moisture content is higher than 15.0 wt.%. Thus, a certain amount of biomass needs to be added in the combustor to provide sufficient heat for biomass devolatilization and steam reforming. Tar content in the syngas can also be predicted from the model, which shows a decreasing trend of the tar with the gasification temperature and the S/B ratio. The tar content in the syngas decreases significantly with gasification residence time which is a key parameter.

     

    Mechanical pulping processes, as Thermomechanical pulp (TMP), Groundwood (SGW and PGW), and Chemithermomechanical pulp (CTMP) processes have very high wood-to-pulp yields. Producing pulp products by means of these processes is a prerequisite for the production of printing paper and paperboard products due especially to their important functional properties such as printability and stiffness. However, mechanical pulping processes consume a great amount of electricity, which may account for up to 40% of the total pulp production cost. In mechanical pulping mills, wood (biomass) residues are commonly utilized for electricity production through an associated combined heat and power (CHP) plant. This techno-economic evaluation deals with the possibility of utilizing a biomass integrated gasification combined cycle (BIGCC) plant in place of the CHP plant. Integration of a BIGCC plant into a mechanical pulp production line might greatly improve the overall energy efficiency and cost-effectiveness, especially when the flow of biomass (such as branches and tree tops) from the forest is increased. When the fibre material that negatively affects pulp properties is utilized as a bioenergy resource, the overall efficiency of the system is further improved. A TMP+BIGCC mathematic model is developed based on ASPEN Plus. By means of this model, three cases are studied:

     

    1) adding more forest biomass logging residues in the gasifier,

    2) adding a reject fraction of low quality pulp fibers to the gasifier, and

    3) decreasing the TMP-specific electricity consumption (SEC) by up to 50%.

     

    For the TMP+BIGCC mill, the energy supply and consumption are analyzed in comparison with a TMP+CHP mill. The production profit and the internal rate of return (IRR) are calculated. The results quantify the economic benefit from the TMP+BIGCC mill.

     

    Bio-ethanol has received considerable attention as a basic chemical and fuel additive. It is currently produced from sugar/starch materials, but can also be produced from lignocellulosic biomass via a hydrolysis--fermentation or thermo-chemical route. In terms of the thermo-chemical route, a few pilot plants ranging from 0.3 to 67 MW have been built and operated for alcohols synthesis. However, commercial success has not been achieved. In order to realize cost-competitive commercial ethanol production from lignocellulosic biomass through a thermo-chemical pathway, a techno-economic analysis needs to be done.

     

    In this work, a thermo-chemical process is designed, simulated, and optimized mainly with ASPEN Plus. The techno-economic assessment is made in terms of ethanol yield, synthesis selectivity, carbon and CO conversion efficiencies, and ethanol production cost.

     

    Calculated results show that major contributions to the production cost are from biomass feedstock and syngas cleaning. A biomass-to-ethanol plant should be built at around 200 MW. Cost-competitive ethanol production can be realized with efficient equipments, optimized operation, cost-effective syngas cleaning technology, inexpensive raw material with low pretreatment cost, high-performance catalysts, off-gas and methanol recycling, optimal systematic configuration and heat integration, and a high-value byproduct.

  • 5.
    He, Jie
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Björkqvist, Olof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Zhang, Wennan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Techno-economic evaluation of a mechanical pulp mill with gasification2013In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, no 3, p. 349-357Article in journal (Refereed)
    Abstract [en]

    Mechanical pulping processes, including thermomechanical pulp (TMP), groundwood (SGW andPGW), and chemithermomechanical pulp (CTMP) processes, each have a very high wood-to-pulp yield. Producing pulp by means of these processes is a prerequisite for paper (such as printing paper and paperboard) grades requiring high printability and stiffness. However, mechanical pulping processes consume a great amount of electricity, which may account for up to 40% of the total pulp production cost.

    In mechanical pulping mills, wood (biomass) residues are commonly utilized for electricity production through an associated combined heat and power (CHP) plant. This techno-economic evaluation deals with the possibility of utilizing a biomass integrated gasification combined cycle (BIGCC) plant in place of the CHP plant.

    Implementing BIGCC in a mechanical pulp production line might greatly improve the overall energy efficiency and cost-effectiveness, especially when more biomass from forest (such as branches and tree tops) is available. When the fibre material that negatively affects pulp properties is utilized as a bioenergy resource, the overall efficiency will be further improved. A TMP+BIGCC mathematical model is developed with ASPEN Plus. By means of modeling, three cases are studied:

    1) adding more forest biomass logging residues in the gasifier,2) adding the reject fibres in the gasifier, and3) decreasing the TMP-specific electricity consumption (SEC) by up to 50%.

    For a TMP+BIGCC mill, the energy supply and consumption are analyzed in comparison with a TMP+CHP mill. The production profits are evaluated.

  • 6.
    Logenius, Louise
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Engberg, Birgitta A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Nelsson, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Holmen Paper.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Mechanical testing methods for evaluation of the mechanical properties of sulphonated wood2013Conference paper (Other academic)
  • 7.
    Niskanen, Kaarlo
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Lagra kol i form av trämaterial2014Other (Other (popular science, discussion, etc.))
1 - 7 of 7
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